1. Field of the Invention
The invention relates to a magnetic recording head. More particularly, the invention relates to a magnetic recording head having a patterned gap layer along a gap in the head to reduce localized empty space in the gap, and a method of making the same.
2. Description of the Related Art
There has been a great demand for increasing the data throughput of magnetic tape transport systems used in conjunction with high-speed digital computers. In order to utilize the high-speed capabilities of these computers, it is necessary to increase the amount of data stored on a magnetic tape and to increase the speed at which the data is written to or retrieved from the magnetic tape media.
To increase the data storage capacity of the tape transport systems, the areal density of the magnetic tape media which stores the data must be increased. Areal density is defined as the number of units of data stored in a unit area of the tape. Areal density is characterized by two attributes: linear density and track density. To increase the areal density of a magnetic tape media, one must increase either or both, the linear density and track density of the magnetic tape.
Track density is defined as the number of data tracks per unit width of magnetic tape. Two characteristics associated with track density are track width, defined as the actual width of an individual data track; and track pitch, defined as the distance from the center of one data track to the center of a neighboring data track. As magnetic tape head size decreases, the track pitch can be decreased and track width is decreased, thereby increasing track density.
An example of the increasing track density can be seen by comparing the StorageTek 4480 18-track tape drive system with the StorageTek 4490 36-track tape drive system. Both systems support a half-inch magnetic tape contained in a 3480-type cartridge. The magnetic tape used in the 4480 18-track tape drive system has a track pitch of approximately 630 xcexcm and a track width of approximately 540 xcexcm. The magnetic tape used in the 4490 36-track tape drive system has a track pitch of approximately 315 xcexcm and a track width of approximately 285 xcexcm. Thus, the track width of the 36-track system is approximately half the track width of the 18-track system. Also, the distance between data tracks in the 36-track system is approximately a third of the distance between the data tracks in the 18-track system.
With high track density magnetic recording heads such as in the 36-track system, because the distance between data tracks is reduced, slight imperfections in the heads will have a more significant impact on the performance and/or the quality of the tape heads. Naturally, a small imperfection in a small area will have a greater impact and be more significant than the same small imperfection in a larger area.
Moreover, in magnetic recording heads, especially magneto-resistive thin film tape heads, a gap length between a substrate and a closure is one of the critical parameters in determining the recording performance of the tape head. Currently, the gap length is controlled by the thickness of the gap layers deposited in the gap between the substrate and the closure. This gap length should be approximately equal to the thickness of the deposited gap layers, barring any contamination. With a magnetic recording head having a flat closure, the substrate has read and/or write tracks disposed on and extending from a gap side surface of the substrate to form the recording module. Then, the recording module is bonded to the flat surface on the closure. After closing or bonding the closure and the recording module, the tape head is ground and lapped such that a smooth contoured surface is obtained.
The tape head of the present invention has a substrate and a closure separated by a gap. The gap layers disposed in the gap include a first gap layer, which comprises a recording track layer deposited on the substrate and a patterned gap layer deposited on a flat surface of the closure. The first gap layer has a first nonplanar topography along a gap side surface of the first gap layer, which would normally create localized air space along the gap. However, in the present invention, the patterned gap layer deposited on the substantially planar surface of the closure has a second topography along the gap side surface of the patterned gap layer that inversely corresponds to the first nonplanar topography. As a result, the gap is substantially filled by the first gap layer and the patterned gap layer. By filling the localized air space in the gap, microchipping is reduced and/or eliminated in the tape head of the present invention.
Specifically, in the present invention, the first gap layer has a first nonplanar topography along the gap that includes recesses having a first thickness. The patterned gap layer has a second topography along said gap that inversely corresponds to said first nonplanar topography. Accordingly, the patterned gap layer is etched to define portions corresponding to the recesses and having a second thickness substantially equal to first thickness so as to substantially completely fill the recesses and thereby the gap.
The present invention further relates to a method of making a multi-track tape head for at least one of reading from and writing to a medium. The method comprises the steps of: (1) forming a recording track on a substrate, where the recording track has a first nonplanar topography along a gap side surface of the recording track; (2) applying a gap layer to substantially an entire surface of a gap side surface of a closure, where the gap side surface is substantially planar; (3) etching the gap layer to form a patterned gap layer with a second topography inversely corresponding to the first nonplanar topography; and (4) bonding the substrate and the closure together.
It is an advantage of the invention to reduce or eliminate the air space along the gap.
It is a further advantage of the invention to substantially completely fill the gap of the tape head.
It is a further advantage of the invention to reduce or eliminate microchipping in the gap of a tape head.
It is a further advantage of the invention that the production of debris, which can get sucked into the gap of the tape head and cause corrosion, can be reduced or eliminated.
It is a further advantage of the invention to provide a tape head having improved performance.